"They're coming in to perform I think on the third or fourth live show," he said. "But that's the only role they'll play."

Cowell also ruled out exploiting the One Direction fanbase for ratings, saying: "They're all One Direction fans and I don't like the idea of databasing and all that kind of stuff, because I like people to make their own mind up.

"I communicate with them through Twitter and stuff like that. They know what we're doing, but it's always their choice."